Electric selective signal receiving apparatus



June 15, 1937. s UTSTRQM 2,083,849

ELECTRIC SELECTIVE SIGNAL RECEIVING APPARATUS v Filed Nov. 21, 1955 4Sheets-Sheet 1 1 iii/"9:1. 5 M 111 L Far/ya? i ('00/V7ffi/9'C77A/GH/lorne y.

A. S. LlTSTRM ELECTRIC SELECTIVE SIGNAL RECEIVING APPARATUS June 15,1937.

Filed NOV. 21, 1935 Sheets-Sheet 2 June 15, 1937. A. s: LITSTROMELECTRIC SELECTIVE S IGNAL RECEIVING APPARATUS Filed Nov. 21, 1935 4Sheets-Sheet '4 In ven/or'."

Patented June 15, 1937 Axel Sigurd Litstriim, Stockholm, SwedenApplication November 21, 1935, Serial No. 50,912 In Sweden November 23,1934 3 Claims.

The present invention relates to an electric selective signal receivingapparatus which upon receiving a signal consisting of a certainpredetermined number of partial signals or signal 5 components ofsubstantially equal duration, the

length of which must lie between a certain minimum, and a certainmaximum, and intervals, the length of which must not exceed a certainmaximum duration, efiects automatic indication, for

instance actuation of an alarm bell or the like.

The invention is particularly concerned with an apparatus of this typewhich comprises a receiver having a receiving relay for receiving thesignal components or dashes, and a counting device for counting thesignal components and for effecting indication after counting apredetermined number of signal components, and a preparation and re-setdevice, such as a locking relay, for the counting device which relay isprovided with a locking circuit so that after energization it will holditself in energized or Working position in which it maintainsthecounting device prepared for counting.

Between the signal receiving relay and the preparation and re-setdevice, or locking relay, there are connected a number of time measuringdevices, each of which is adapted to actuate a contact means, such as arelay, associated with the same, after such time measuring device hasbeen operating during a certain predetermined length of time.

One of said time measuring devices is a minimum time measuring devicewhich serves to check that the signal components reach the predeterminedminimum duration, this device being put in and out of operation by thesignal receiving relay and serving, upon minimum duration of a dashbeing reached, through its contact means to cause the preparation andre-set device of the counting device to operate.

A time difierence measuring device, which serves to check that thesignal components do not exceed the predetermined maximum duration, anda space measuring device, which serves to control that the intervals orspaces between the signal components or dashes do not exceed thepredetermined maximum duration, are adapted by means of their contactmeans to control the locking circuit of said preparation and re-setdevice in such manner that said locking circuit is opened, or isdeenergized, when the contact means associated with either of said timemeasuring devices operates upon maximum duration of the dash, or uponmaximum length 0f the space, being reached. The minimum time measuringdevice through its contact means causes the time difference measuringdevice to start operation upon a dash reaching minimum duration, andstops operation of said device when the dash ceases, and then causes thespace measuring device to operate, the contact means of which isactuated after the lapse of the maximum duration of the space and thenremains in actuated position until the next dash has reached minimumduration. 10

In case the time difference allowed between minimum and maximum durationof the signal components is equal to the permissible maximum duration ofthe interval or space, the same time measuring device may serve to checkthe differ- 1 ence as well as the space, and in such case this combinedtime difference and space measuring device is connected to the minimumtime measuring device in such manner that, when the dash terminates, thefirst named device is first put out of operation by the last-mentioneddevice, and then again caused to operate to measure the space.

It is the purpose of the present invention to provide a simplifiedsignal receiving apparatus of 25 this type which shall comprise theleast possible number of parts, and in particular, to provide anapparatus in which, when signals, such as Morsesignals, are receivedwhich are of less duration than the permissible minimum duration of a 30signal component, only a single movable contact in the signal receivingrelay operates, while the other parts and elements of the apparatus areleft undisturbed.

With this purpose in view the present inven- 35 tion is broadlycharacterized by the signal receiving relay being provided with a singlemovable contact, and by the minimum time measuring device beingconnected to said signal receiving relay in such manner that saidcontact 40 puts said device in operation at the commencement of'a dashreceived and puts the same out of operation when the dash terminates,and that the preparation and re-set device is provided with a secondlocking circuit which is controlled 45 by the said contact of the signalreceiving relay in such manner that said locking circuit is closed Whilea dash is being received, and that an impulse circuit for the countingdevice is controlled by the contact means associated with the mini- 50mum time measuring device in such manner that said circuit is closed bysaid contact means when the minimum time measuring device is put out ofoperation owing to the dash terminating.

According to the invention the contact means 55 associated with the timemeasuring devices are always connected to the latter. By thisarrangement the necessity is avoided of providing said contact meanswith special locking circuits, and of providing the relays of theapparatus with specialcontacts for closing and opening such lockingcircuits, whereby the number of movable contacts is decreased and theapparatus is simplified.

The accompanying; drawings illustrate by Way of example anddiagrammatically a few constructional forms of the invention. Fig. 1 isa Wiring diagram of a signal receiving apparatus according to theinvention. Fig. 2 is a diagram illustrating the operation of the variousparts of the apparatus illustrated in Fig. 1 when a correct signal isreceived. Fig. 3 is a diagram 11- lustrating the function of theapparatus when a dash lasts too long, and Fig. 4 is a diagramillustrating the function when a space is too long. Fig. 5 is a wiringdiagram of a slightly modified signal receiving apparatus, and Fig. 6 isa wiring diagram of a third constructional form.

The apparatus illustrated in Fig. 1 consists of a radio receiver, whichmay be a three valve receiver diagrammatically indicated at M, and aselector combined therewith. The entire apparatus is assumed to beconnected to direct current mains carrying a voltage of 110 volts.

The drawings show all parts in the positions occupied when the apparatusis connected to the mains but no signal is received by the receiver.

The selector comprises in this case two time measuring devices and acounting device with associated relays. Connected in the anode circuitof the end valve of the receiver, through suitable amplifiers, ifdesired, is the winding ll of a signal receiving relay l which isprovided with a single change-over contact l2, and which is energized aslong as no signal is received.

The signal receiving relay may also consist of a polarized relay theenergization of which is. changed in a certain direction when a signalis received.

In the constructional form illustrated in Fig. 1 the time measuringdevices consist of condensers i5 and 25 connected in parallel with largeresistances i6 and 26, respectively, through which they are dischargedwhen a potential impressed upon the same is removed.

One side of the condenser l5 which together with its dischargeresistance l6 forms the minimum time measuring device, is connected tothe lower contact of relay and is normally connected to the negativeterminal over the changeover contact 52. The same side of the condenseris also connected to a grid 83 of a valve 8 which latter is alsoprovided with a cathode 82 indirectly heated by means of a filament 8|,a screen grid 84, and an anode or plate 85. Connected in the anode orplate circuit of this valve is the winding 2| of the associated relay 2which is provided with a change-over contact 22 and a normally opencontact 23. The other side of the condenser I5 is connected to a tap +bof a voltage divider Hi4.

One side of the other condenser 25 which together with its dischargeresistance 26 forms the combined time difierence and space measuringdevice, is normally connected to the negative terminal over the normallyclosed contact 33 of a relay 3 which is provided with two windings 3|and 32. The same side of the condenser 25 is connected to a grid 63 of avalve 9 which latter is also provided with a cathode 92 indirectlyheated by means of a filament 9|, a screen grid 94 and an anode or plate95.

Connected in the anode or plate circuit of this valve 9 is the winding4| of the associated relay 4 which is provided with a normally closedcontact 42. The other side of the condenser 25 is connected to the tap+1) of the voltage divider The anode circuits of both valves areconnected to one another and, preferably through a milliampere-meterI51, to the voltage divider I04 at +a.

As above mentioned, when no signal is received, relay is energized, andthe negative terminal is thus connected to the lower contact so that thegrid 83 of the valve 8 receives a negative potential, and therefore, nocurrent can pass through the valve 8.

The upper contact of relay is connected to I a contact 54 in a lockingcircuit of a relay 5 which forms the preparation and re-set device, orlocking relay, of the counting device, and which is provided with twowindings 5| and 52 and three normally open contacts 53, 54 and 55.

The contact 53 is connected to the changeover contact 22 of relay 2 and,upon energization of the relay 5, closes a circuit either through thewinding 3| or through the winding 32 of relay 3.

The windings 3| and 32 are so arranged that the fields producedcounteract one another, so that the contact 33 of the relay 3 will besure to close momentarily when the current is changed over from one ofthe windings to the other.

The contact 55 of relay 5 is connected to the contact 42 of relay 4, andalso with a locking winding 6| of the counting device 6 and with acontact 12 of a relay 1.

In addition to the said locking winding 6|, the counting devicecomprises a winding 62 which when energized efiects movement of aratchet wheel 63 which is provided with teeth 64 and a cam 65. Theratchet wheel 63 is actuated by a spring or the like which tends tomaintain the wheel in a certain starting or initial position. Whenenergized, the locking winding 6| attracts, against the action of aspring, a pivoted armature 66, which then allows a spring-actuated pawl61 to engage the ratchet wheel 63. Said pawl 61 is pivoted to aspring-actuated armature 68 which is attracted by the winding 62 whenthe latter is energized.

The counting device has two normally closed contacts 69 and which areopened when the ratchet wheel 63 has moved three steps.

The contact 69 is connected in the circuit of a signal lamp |0| andopens this circuit when the counting device arrives in the indicationposition.

The contact 66 is connected in the circuit of the winding ll of a relay1 and opens said circuit when the counting device arrives in theindication position. Said relay 1 is normally energized, and itscontacts 12, 13 and 14 are then open. Upon deenergization of the winding1| the contacts of the relay I are closed, and a number of alarm bellsI00 which are connected to the contacts 13 and 14, are energized andstart ringing.

The signal lamp IDI, which is normally dark, and the circuit of which isopened by the contact 69 when the counting device has received andcounted three correct dashes, is connected in parallel to the bells I66.The contact I2 of relay 1 serves to close a locking circuit through thelocking Winding 6| of the counting device 6 when the signal receivingapparatus is moved to indication position.

As above mentioned, the entire receiving apparatus is supplied withcurrent from direct current mains which may be the electric light mainsof a vessel. A main circuit breaker IE2 serves to switch on and off theentire signal receiving apparatus. The current to the various relays andthe various voltages for the valves are taken out from the voltagedividers I 53 and I04. The relay currents are taken out from the voltagedivider I83 between the negative conductor and the tap +cZ, and thevoltages for the valves 8 and 9 from the other voltage divider IIM at+a, +2) and Two voltage dividers are used to make the potentials of thevalves independent of the closing and opening of the circuits of therelays.

The valves of the receiver M are indicated by their filaments H15 shownin the lower right-hand corner of Fig. 1, where the filaments 8| and SIof the valves 8 and 9 are also shown. All filaments of the valves areconnected in series with each other and with a self-regulating ironresistance I06 which serves the purpose of automatically maintaining thefilament current constant.

Also in series with the filaments is the contact Gil of the countingdevice 6 and the winding II of relay 7.

If one of the filaments breaks, the winding H will immediately bedeenergized, whereby the contacts 75, 14 are closed so that the alarmbells I start ringing, and the lamp IOI is lit.

The anode voltage of the valves of the receiver is taken out at I08.

The signal receiving apparatus above described makes an indication assoon as three signal components or dashes of correct duration andseparated by correct intervals or spaces have been received in unbrokensuccession, but is always returned to starting or initial position ifany dash is longer than the prescribed maximum duration, or shorter thanthe prescribed minimum duration, or if any space exceeds the prescribedmaximum duration of the spaces.

The operation of the signal receiving apparatus will now be described.In the present case it is assumed that the clashes shall have a minimumduration of three seconds and a maximum duration of five seconds, andthat the length of the spaces must not exceed two seconds. The operationof the relays and of the time measuring devices when a correct sequenceof dashes is received, is illustrated in Fig. 2. The operation of thedevice when a dash has too long a duration, is illustrated in Fig. 3,and when a space is too long, in Fig. 4.

In Figs. 2, 3 and 4 the shaded surfaces denote the duration of thedashes received, the intermediate surfaces denote the spaces between thedashes, each of the horizontal narrow lines denotes a relay andindicates that its winding or windings are deenergized, the heavyhorizontal lines denote the periods during which the respective relaysare energized, and the heavy vertical lines denote when one of thecondensers I5 and 25 has been discharged to such extent that the anodecurrent in the corresponding valve is sufficient to cause the relayincluded in its anode circuit to close.

When a signal is received by the receiver M, at A in Fig. 2, the WindingII is deenergized, and the change-over contact I2 moves to its upperposition. The condenser I5 therefore begins to discharge through theresistance I6, and the negative potential is gradually removed from thegrid 83 of the valve 8. Through the valve 8 a gradually increasingcurrent will flow which after three seconds, that is to say, when thedash has attained minimum duration, at B in Fig. 2, becomes so strongthat relay 2 is energized and attracts its contacts 22 and 23.

When relay 2 closes, a circuit is closed from the negative conductorthrough the front contact 23 and the winding 52 to the tap +d on thevoltage divider I03, and relay 5 becomes energized. Relay 5 closes itscontacts 53, 54 and 55.

Contact 53 of relay 5 closes a circuit through the winding 3| of relay 3which circuit was prepared by the energization of relay 2 causingcontact 22 to move to its lower position. Relay 3 is thus energizedthrough a circuit from the.

negative conductor through contact 53, contact 22 and winding 3i to thetap +d on the voltage divider I 03.

Contact 54 of relay 5 closes a locking circuit through its winding 52from the negative conductor through contact I2 of relay I, contact 54and winding 52 to the tap -{-d on the voltage divider I53. A lockingcircuit is also closed from the negative conductor through contact 55,contact 42 of relay 4, and winding 5| of relay 5 to the tap +d on thevoltage divider I05. Relay 5 will afterwards be energized during theentire period of receiving the other dashes of the signal and during thespaces between the same, provided that all dashes and all spaces havecorrect duration.

The closing of relay 5 also causes a circuit to close from the negativeconductor through contact 55 and the winding 6| of the counting device 6to the tap +d on the voltage divider I03. This winding is energized andattracts the armature 56 against the action of its spring so that thepawl 67 is allowed to engage one of the teeth 6 on the ratchet wheel 63.The counting device is thus prepared for operation which action takesplace as soon as the first dash ceases.

The relay 3 being energized, its contact 33 is opened so that thecondenser 25 begins to discharge through the resistance 26 and thenegative potential is gradually removed from the grid 93 of the valve Q.The period of discharge of the condenser 25 is so timed that after twoseconds the potential on the grid 93 is sufficiently positive for theanode current through the valve to energize the winding 4! so that thearmature 42 is attracted. However, if, as it is here assumed, the firstdash ceases within the prescribed time, that is to say, after three butbefore five seconds from the beginning of the signal component at A inFig. 2, the relay 4 will not be energized.

When the first dash ceases, at C in Fig. 2, the winding I I of relay Iis energized, and the change-over contact I2 is moved to its lowerposition. The grid 83 of valve 8 then receives negative potential, thecondenser I5 is charged, and the relay 2 is deenergized, since the anodecurrent ceases to flow through the valve 8. The contact 22 of relay 2then moves from its lower position so that relay 3 is momentarilydeenergized. The contact 33 of relay 3 is then momentarily closed sothat the grid 93 of the valve 9 momentarily receives negative potential,and the condenser 25 is charged.

When the contact 22 has been closed in its up per position the winding32 of relay 3 is energized through a circuit from the negative conductorthrough contact 53 of relay 5, contact 22 of relay 2, and the winding 32to the tap +d of the voltage divider I03.

Simultaneously the circuit through the impulse or step winding 62 of thecounting device 6 is closed, and said winding attracts its armature 68so that the ratchet wheel 63 is moved one step.

The energization of relay 3 again opens its contact 33, and thecondenser 25 again begins discharging through the resistance 26 forchecking the length of the space. During the space, as long as the relay4 is not energized, the relay is maintained energized through theabove-mentioned circuit from the negative conductor through contact 55,contact 42 of relay 4, and winding 5i to tap +cZ on the voltage dividerI03.

If a second dash is received at D in Fig. 2, before the space hasattained the prescribed maximum duration of two seconds, relay l isagain deenergized and its contact l2 moves to its upper position. Thecondenser i5 commences discharging through the resistance i6, and thenegative potential on the grid 83 is gradually changed to positive. Twoseconds from the beginning of the space, at E in Fig. 2, the potentialon the grid 93 of valve 9 has been raised so much that the anode currentin said valve is strong enough to energize the winding 4| of relay 4sufficiently for opening the contact 42. The current through the winding5| of relay 5 is thus broken, but said relay is still energized sincethe wind ing 52 is now again supplied with current through contact [2 ofrelay l and contact 5 2 of relay 5.

When the second dash has attained minimum duration, at Fin Fig. 2, theanode current through the valve 8 is strong enough to close relay 2.When the contact 22 moves from its upper position to its lower position,the relay 3 is momen- -tarily deenergized so that its contact 33 closes,

and the grid 93 of the valve 9 receives negative potential so that itsanode current ceases, and therefore, relay 4 is deenergized. When relay3 is again energized through its winding 3|, the contact 33 is againopened, and the condenser 25 again commences discharging in order tocheck that the second dash does not exceed maximum duration.

If also the second dash ends within the prescribed time, at G in Fig. 2,the same operations are repeated as those above described in connec tionwith the first dash, and the ratchet wheel 63 is moved a second step.When afterwards the third dash is received, the same operations takeplace as when the second dash was received, and if the third dash alsoends within the prescribed length of time, the winding 62 of thecounting device will be energized for the third time and moves theratchet wheel 63 a third step. The cam 85 then opens the contacts 69 and50, so that the current through the filaments of all valves 'in thereceiving device and through the winding H of relay 1 is broken. Whenrelay 1 deenergizes, its contacts 12, 13 and 14 close.

The contacts 1'3 and 14 close a circuit through the alarm bells Hillwhich start ringing. Since the contact 63 of the counting device isopen, the

signal lamp HH will not be lit. The contact 12 closes a circuit throughthe locking winding 6! of the counting device 6 which prevents thecounting device from returning to initial position when the other relaysof the receiving device are deenergized. The alarm bells will thereforecontinue to ring until the operator opens the main circuit breaker I02of the signal receiving apparatus.

For restoring the apparatus to normal position after the bells IIJU havecommenced ringing, it is only necessary to open the main circuit breakerI02.

As above mentioned, the signal receiving apparatus is so constructedthat if the signals are incorrect in any manner, it will immediatelyreturn to initial position. The operations which take place when variouskinds of incorrect si nals are received, will now be described.

If the first dash is too short, that is to say, if it ends before 13 inFig. 2, the relay I will immediately be energized when the dash ends,and will therefore attract the contact l2, so that the discharge of thecondenser I5 is interrupted, and said condenser as well as the grid 83receive negative potential. Therefore, the anode current through thevalve 8 will not attain such strength that the relay 2 closes. Theapparatus will then again be in normal condition.

If the second or third dash is too short, and if it ceases after therelay 4 has become energized, that is to say, between E and F or betweenI and K in Fig. 2, the following operation takes place. When the dashceases, the winding 1 I of relay l is energized, the grid 83 is suppliedwith negative potential, and the condenser I5 is charged. Since therelay 2 has not yet been energized and, therefore, its contact 23 isopen, and since relay 4 is energized and its contact 42 is open, andtherefore, the circuit through the winding 5| of relay 5 is broken, therelay 5 will be deenergized when the contact I2 leaves its upperposition and breaks the locking circuit through contact 54 and winding52. When the relay 5 is deenergized, the relay 3 and the winding 62 willalso be deenergized owing to the contact 53 being opened, and likewise,the winding 6! will be deenergized since the contact 55 opens. Owing torelay 3 being deenergized, the grid 93 of valve 9 again receives fullnegative potential, so that relay 4 is deenergized, and the apparatus isthen again in normal condition.

If a dash, for instance the second dash, is too long, that is to say, ifit lasts more than two seconds over the minimum duration, then relay 4will be energized, as indicated at F1 in Fig. 3, so that the contact 42breaks the locking circuit through winding 5|. When afterwards the dashends, at G1 in Fig. 3, and relay l is energized, contact l2 breaks thelocking circuit through winding 52 and applies negative potential togrid 83 of valve 8 so that relay 2 is released and contact 23 breaks thecircuit through winding 52, and relay 5 is deenergized.

When relay 5 deenergizes, the circuits through relay 3 and throughwinding 61 of the counting device are opened, so that said device isreleased and returned to normal position. The relay 3 being deenergized,its contact 33 closes and the grid 93 of the valve 9 is supplied withfull negative potential, so that the anode current ceases and the relay4 in the anode circuit is deenergized. The receiving apparatus is thenagain in normal condition.

If a space is too long, the relay 4 will be energized when two secondshave elapsed from the beginning of the space, as indicated at D1 in Fig.4. During the space, Winding 5| only of relay 5 is energized over thelocking circuit through contact 42 of relay 4, and therefore, when saidrelay opens said contact 42, relay 5 will be deenergized, so that thecircuits through the relay 3 and through the windings BI and 62 of thecounting device are broken. When relay 3 is deenergized, the grid 93 isagain supplied with negative potential, and the relay 4 is deenergized,after which all parts of the apparatus are again in normal condition.

If disturbing telegraphic messages or atmospheric disturbances arereceived by the receiver during a space, the receiving relay I will bemomentarily deenergized, but this fact has no influence on the condenser25 which continues to discharge during two seconds from the beginning ofthe space.

The apparatus above described is also arranged in such manner that if afilament in any of the valves in the apparatus burns out, the alarmbells will immediately start ringing. Simultaneously, however, thesignal lamp i! is lit which shows that there is a fault in theapparatus. As will be understood from a consideration of Fig. 1, if anyof the filaments 8i, 9!, N15, or 35 breaks, the current through thewinding ll of relay 1 will be broken. The contacts of the relay thenclose, and the circuit is closed through the alarm bells I55, and alsothrough the contact 69 of the counting device, which is assumed not tooccupy indication position, to the signal lamp Illl which is lit.

The constructional form illustrated in Fig. agrees on the whole withthat above described, and the same reference numerals are therefore usedto denote similar parts. The receiver M, relays l, 2, 3, 4, and 5,counting device 6, condensers l5 and 25 and valves 8 and 9 are connectedwith one another in the same manner as above described in connectionwith Fig. 1, and are arranged in the same manner and have the samenumber of contacts, with the following exceptions:

Relay 5 is in this case provided with only one winding 52 which isconnected, besides with the contact 23 of relay 2, with the lockingcircuit through contact 42 of relay 4 and contact 55 of relay 5. Saidcontact 55 is in this case connected with contact 22 of relay 2, and isalso connected with the locking winding 5| of the counting device 6 inthe same manner as in Fig. 1.

Besides the contact 55, relay 5 has only one further contact 55 whichserves to close the second locking circuit for the relay 5 over contactl2 of relay i when deenergized, as in Fig. 1. It will be understood fromthis description that relay 5 of Fig. 5 will function in exactly thesame manner as the corresponding relay 5 of Fig. 1.

Relay 3 is provided with an additional contact 35, and relay l isprovided with an additional contact 55, which contacts serve to close ashortcircuit for the locking winding 5! of the counting device 6 if adash exceeds the maximum duration.

As in the constructional form above described, relays 2, 3 and 5 areenergized when a dash has reached minimum duration. When the permissiblemaximum duration of a dash is reached, relay 4 is operated, and acircuit is then closed from the negative terminal through closed contact55, closed contact 22, closed contact 34, and closed contact 53 to pointI09 and then through resistance HD to tap +d on the voltage divider I03.The winding Si is thus short-circuited, and the counting device 5 isimmediately released. In this case, therefore, deenergization of winding6| is effected at F1 in Fig. 3, and is not dependent upon relay 5 beingfirst deenergized. Therefore, even if, when the dash terminates and therelay 2 deenergizes, its contact 22 should happen to close the circuitthrough the impulse or step Winding 62 of the counting device 5 beforerelay 5 releases and opens contact 55, such energization of winding 62will have no efiect, since winding M is deenergized and has releasedarmature 65.

During normal operation, however, for illustration of which the diagramshown in Fig. 2 will serve also in this case, when relay l is energizedat the end of the permissible space period, at E in Fig. 2, relay 2 isnot energized so that the abovementioned short-circuit through contact53 is not operative to deenergize winding El, which action is notdesired in this case. When, at F in Fig. 2, the dash has reached minimumduration and relay 2 is energized, relay 5 is momentarily deenergized bycontact 22 moving from its upper position, so that contact 35 is openedand renders the above-mentioned short-circuit inoperative before contact22 reaches its lower position, thus giving relay 3 time to releasecontact 33 and preventing the circuit from being closed by contact 22,which is not desired at this stage.

The counting device 5 has in this case only one normally closed contactEll which is opened by the ratchet wheel 53 when the latter has movedthree steps. Said contact 55 is connected in a circuit from the positiveterminal through winding ll of relay l, contact 55, self-regulating ironresistance 35, filaments 9i and iii of valves 5 and 8, and filaments 955of the receiver valves, to the negative terminal. shunted across windingH and contact 55 is a lamp lull in series with a resistance Ill normallypreventing the lamp from burning. When three correct signals have beenreceived and the counting device 5 opens the contact 55, sufiicientcurrent will flow through the shunt to cause the lamp lfli to light, butif one of the filaments in the circuit burns out while contact till isclosed, the lamp llil will not be lit.

In either case relay 7 will be deenergized and close its contacts. Inthis case contact F2 serves to apply negative potential to the lowersides of condensers l5 and 25, thus putting the same and the valves 8and 9 out of operation, while contact 73 closes a circuit through thealarm bells Hill and a battery 1 E2. The bells will ring when relay 1 isdeenergized, whether by the counting device 5 opening contact 65 or bythe circuit being broken by one of the filaments burning out.

Fig. 6 shows a wiring diagram of a constructional form of the inventionin which three time measuring devices are employed. Each of the timemeasuring devices consists of a condenser connected in parallel with arelay winding and in series with a resistance. Normally, or when thetime measuring apparatus is not operative, the condenser and relaywinding are short-circuited by means of a shunt connection, so that nocurrent flows through the winding, but when the device is to operate theshunt connection is broken and potential is applied to the condenser andrelay winding.

The drawings show all parts in the positions occupied when no signal isreceived by the receiver.

As in the constructional forms above described, M denotes the receiverto which the winding 2i i of a signal receiving relay 2D! is connected.This relay has a single movable contact 2H2 which in the position shownapplies positive potential to point 225 between condenser 225 andresistance 225 of the minimum time measuring device 252, so that nocurrent flows through winding 2N which is shunted across said condenser225.

When a. dash is received so that winding 2H attracts contact 2E2, theshort-circuit of condenser 225 and winding 22i is removed, and ourrentbegins to flow through the same. After the lapse of a period of timecorresponding to the prescribed minimum duration of a dash, thecondenser 225 has been charged to a potential sulficient to cause astrong enough current to flow through winding 22! to permit this windingto operate the contacts 222 and 223.

Contact 223 closes a circuit over contact 242 of the space measuringdevice 204 through winding 25! of the locking relay 205, which operatesits contacts 254 and 255. Contact 254 closes a locking circuit forwinding 252 of said relay 205 over contact 2!2 of relay 20!. Contact 255closes a locking circuit for winding 25! over contact 242 of the spacemeasuring device 204 and contact 232 of the time difierence measuringdevice 203. Contact 255 also closes a circuit through winding 26! of thecounting device 205, which winding attracts armature 266 and thusprepares this device for operation.

Contact 255 also applies positive potential to the upper sides ofcondensers 235 and 245 of the time measuring devices 203 and 204.Contact 222 when operated, as above stated, breaks the shortcircuitconnection to point 236 between condenser 235 and resistance 234 of thetime difference measuring device 203, but closes the short-circuitconnection to point 243 between condenser 245 and resistance 244 of thespace measuring device 204. No current will therefore flow throughwinding 24! of the last mentioned device.

Therefore, as soon as winding 22! of the minimum time measuring device202 is energized, upon minimum duration of a dash being reached, thetime difference measuring device 203 is put in operation and commencesto check the difference between minimum and maximum duration, to controlthat the dash does not exceed the maximum duration permitted.

If the dash exceeds the prescribed maximum duration, the condenser 235has been charged to a potential sufiicient to cause a strong enoughcurrent to fiow through winding 23! of the time difference measuringdevice 203 to permit said winding to operate the contacts 232 and 233.

Contact 233 closes a circuit from the positive terminal through saidcontact to point 208 between winding 26! and resistance 209, and throughsaid resistance 200 to the negative terminal. Winding 20! is thusdeenergized, so that the counting device 206 is no longer prepared foroperation.

Contact 232 breaks the locking circuit through winding 25! of relay 205.When the dash ends and relay 20! and winding 22! are deenergized,contact 2 2 breaks the locking circuit through winding 252, and contactbreaks the original circuit through winding 25! of relay 205, whichdeenergizes, whereby winding 23! of the time difference measuring device203 is also deenergized and the entire apparatus is returned to normal.

Contact 232 also breaks the impulse circuit for winding 202 of countingdevice 200, which circuit might otherwise be closed at contact 223, ifthe contacts of relay 205 have not been returned to normal before saidcontact 223 is returned to normal upon deenergization of winding 22 Saidimpulse circuit will be described here below.

If, on the other hand, the dash does not exceed maximum duration,winding 2H of the time difference measuring device 203 will not havetime to operate its contacts before the dash ends.

In such case, when the dash ends, winding 2!! of relay 20! isdeenergized and contact 2!2 is returned to normal, thereby applyingpositive pocounting device 208 is of the same construction as I thatabove described in connection with Figs. 1 and 5.

Contact 222 when returned to normal position, applies positive potentialto point 236 whereby winding 23! is deenergized and the time difierencemeasuring device 203 is put out of operation.

Simultaneously, the positive potential is removed from point 240, sothat current is allowed to fiow from the positive terminal over contact255 to condenser 245 and winding 24! of the space measuring device 204,which is thus put in operation to measure the space.

After the lapse of the space period the condenser 245 has been chargedto a potential sufficient to cause enough current to flow throughwinding 24!, which becomes energized and opens contact 242, therebybreaking the locking circuit through winding 25! of relay 205.

If a second dash has not been received when contact 242 opens, so thatrelay 20! is still deenergized, the locking circuit through Winding 252l of relay 205 is open at contact 2!2, and therefore, relay 205 will bedeenergized as soon as contact 242 opens, thereby deenergizing winding26! so that the counting device 203 is returned to normal.Deenergization of relay 205 also breaks the current to the spacemeasuring device 204 which is returned to normal.

On the other hand, if, when contact 242 opens, a second dash is beingreceived, relay 20! is energized and the locking circuit through Winding252 of relay 205 is closed by contact 2!2, so that relay 205 will remainenergized in spite of the contact 242 being opened.

If such second dash does not last long enough for the minimum timemeasuring device 202 to operate, the locking circuit through winding 252Will be broken at contact 2!2 when the dash ends, and relay 205 willthen be deenergized and the apparatus returned to normal, as abovedescribed.

If, however, the second dash reaches the prescribed minimum duration,the minimum time measuring device 202 will operate so that its winding22! attracts contacts 222 and 223. Point 246 is thus connected overcontact 222 to the positive terminal, so that condenser 245 and winding24! are short-circuited, whereby the space measuring device 204 is putout of operation, and contact 242 is again closed in normal position.Simultaneously, positive potential is removed from point 230, so thatthe time difierence measuring device 203 is again put in operation tocheck the maximum length of the dash, after which the operation proceedsin the manner above described.

When the prescribed number of correct dashes have been received andcounted by the counting device 206, the latter efiects indication. Saiddevice may, of course, be connected to the alarm bell circuit in thesame manner as above described and illustrated in Fig. l or Fig. 5.Diagrammatically, and for the purpose of illustration only, Fig.

6 shows the alarm bells 260 connected in a circuit including a battery2m and a contact 269 which is closed by the wheel 263 of the countingdevice 296, when the correct sequence of dashes has been received.

Obviously, since the winding 6! of the counting device is energizedsimultaneously with relay 5, these two parts may be combined into one,in such manner that the winding 6|, or 26!, operates the contacts 53,54, 55, or 25 2, 255, in which case the winding 6!, or 26!, should, ofcourse, be connected in the manner above described in respect of thewinding of relay 5, or 205.

It will readily be understood that the constructional forms illustratedin Figs. 1 and 5 may easily be modified in the manner above described inconnection with Fig. 6, i. e. by using one time measuring device forchecking the permissible difference between minimum and maximumduration, and another such device for checking the space, instead of asingle such devicecondenser 25, resistance iii, valve 9, and relay 4-with auxiliary relay 3, as above described in connection with Figs. 1and 5.

It will be understood that the constructional forms of the inventionabove described and illustrated in the drawings are only to be regardedas examples, and that the details thereof may be modified in severalvarious ways without departing from the principle of the invention.

I claim:

1. In a signal receiving apparatus of the character described, thecombination of a receiver having a signal receiving relay provided witha single movable contact, a counting device for counting signalsreceived and for effecting indication after receipt of a predeterminednumber of signal dashes, holding and re-set means for said countingdevice, a minimum time measuring device connected to said signalreceiving relay in such manner as to be put in operation by said movablecontact upon commencement of a signal dash received and to be put out ofoperation by said contact upon termination of the dash, contact meansassociated with and adapted to be operated by said device after apredetermined time of operation of said device and to be returned tonormal position by said device being put out of operation, at least onefurther time measuring device connected to said contact means associatedwith said first mentioned time measuring device in such manner as to beput in operation and out of operation by said contact means, contactmeans associated With and adapted to be operated by said second timemeasuring device after a predetermined time of operation of said device,and to be returned to normal position by said device being put out ofoperation, a circuit for initially energizing said holding and re-setmeans for said counting device, said circuit being arranged to be closedby said contact means associated with said firstmentioned minimum timemeasuring device when operated by said device, a locking circuit forsaid holding and re-set means for said counting device arranged to beopened by said contact means associated with said second time measuringdevice upon said contact means being operated after a predetermined timeof operation of said device, a second locking circuit for said holdingand re-set means for said counting device arranged to be closed by saidmovable contact of said signal receiving relay while a signal dash isbeing received, and an impulse circuit for said counting device arrangedtobe closed by said contact means of said first mentioned minimum timemeasuring device when returned to normal position by said minimum timemeasuring device being put out of operation upon termination of a dash.

2. In a signal receiving apparatus of the character described, thecombination of a receiver having a signal receiving relay provided witha single movable contact, a counting device for counting signalsreceived and for effecting indication after receipt of a predeterminednumber of signal dashes, holding and re-set means for said countingdevice, a minimum time measur ing device connected to said signalreceiving relay in such manner as to be put in operation by said movablecontact upon commencement of a signal dash received and to be put out ofoperation by said contact upon termination of the dash, contact meansassociated with and adapted to be operated by said device after apredetermined time of operation of said device and to be returned tonormal position by said device being put out of operation, at least onefurther time measuring device connected to said contact means associatedWith said first-mentioned time measuring device in such manner as to beput in operation and out of operation by said contact means, contactmeans associated with and adapted to be operated by said second timemeasuring device after a predetermined time of operation of said device,and to be returned to normal position by said device being put out ofoperation, a circuit for initially energizing said holding and re-setmeans for said counting device, said circuit being arranged to be closedby said contact means associated with said first mentioned minimum timemeasuring device when operated by said device, a locking circuit forsaid holding and re-set means for said counting device arranged to beopened bysaid contact means associated with said second time measuringdevice upon said contact means being operated after a predetermined timeof operation of said device, a second locking circuit for said holdingand re-set means for said counting device arranged to be closed by saidmovable contact of said signal receiving relay While a signal dash isbeing received, an impulse circuit for said counting device arranged tobe closed by said contact means of said first-mentioned minimum timemeasuring device When returned to normal position by said minimum timemeasuring device being put out of operation upon termination of a dashand by said holding and re-set means, and a short-circuit connection forsaid holding and re-set means arranged to be closed by said contactmeans of said second time measuring device when in operated position.

3. In a signal receiving apparatus of the character described, thecombination of a receiver having a signal receiving relay provided witha single movable contact, a counting device for counting signalsreceived and for eiiecting indication after receipt of a predeterminednumber of signal dashes, holding and re-set means for said countingdevice, a minimum time measuring device connected to said signalreceiving relay in such manner as to be put in operation by said movablecontact upon commencement of asignal dash received and to be put out ofoperation by said contact upon termination of the dash, contact meansassociated with and adapted to be operated by said device after apredetermined time of operation of said device and to be returned tonormal position by said device being put out of operation, at least onefurther time measuring device connected to said contact means associatedwith said first-mentioned time measuring device in such manner as to beput in operation and out of operation by said contact means, contactmeans associated with and adapted to be operated by said second timemeasuring device after a predetermined time of operation of said device,and to be returned to normal position by said device being put out ofoperation, a circuit for initially energizing said holding and re-setmeans for said counting device, said circuit being arranged to be closedby said contact means associated with said first-mentioned minimum timemeasuring device when operated by said device, a locking circuit forsaid holding and re-set means for said counting device arranged to beopened by said contact means associated with said second time measuringdevice upon said contact means being operated after a predetermined timeof operation of said device, a second locking circuit for said holdingand reset means for said counting device arranged to be closed by saidmovable contact of said signal receiving relay While a signal dash isbeing received, an impulse circuit for said device arranged to be closedby said contact means of said firstmentioned minimum time measuringdevice when returned to normal position by said minimum time measuringdevice being put out of operation upon termination of a dash and by saidholding and re-set means, said receiver and said time measuring devicesincluding electric valves having filaments, a circuit includingalarm-giving means, a relay to close and open said circuit, and acircuit including said valve filaments and said relay and a contact insaid counting device.

AXEL SIGURD LITSTRDM.

